Fins are used to enhance convective heat transfer in a wide range of engineering applications, and offer a practical means for achieving a large total heat transfer surface area without the use of an excessive amount of primary surface area. Fins are commonly applied for heat management in electrical appliances such as computer power supplies or substation transformers. Other applications include IC engine cooling, such as fins in a car radiator. It is important to predict the temperature distribution within the fin in order to choose the configuration that offers maximum effectiveness. This exercise serves as a visualization tool for evaluating the effect of shape on fin effectiveness, efficiency, and temperature distribution. In many heat transfer applications, it is desirable to increase the surface area that is available for the heat transfer process; this is particularly true when one desires to dissipate heat to a low conductivity medium such as air. There are three mechanisms by which heat transfer can take place. All the three modes require the existence of temperature difference. The three mechanisms are. 1. Conduction, 2. Convection 3. Radiation

Pradeep Singh, Harvinderlal,Baljit Singh Ubhi[1] had investigated the heat transfer performance of extended surface or finned surface. Design of fin with various extensions such as rectangular extension, trapezium extension, triangular extensions and circular extensions has been considered for the analysis. The heat transfer performance of extended surfaces with same geometry having various shapes of extension and without extension has been compared. About 5% to 13% enhancement in heat transfer can be obtained with these various extensions on fin as compare to same geometry of fin without these extensions. In this thermal analysis, temperature variation along the length of fin at which heat flow occur through the fin is analyzed. Extensions on the extended surface or finned surfaces are used to increases the surface area of the fin in contact with the ambient fluid flowing around it. Since, the surface area increases, it tends to increase the heat transfer due to convection. Thus there will be an increase in overall heat transfer due to conduction and convection. Shivdas S. Kharche&Hemant S. Farkade[2] had investigated the effect of placing notch on the finned surface. Different shapes of notched such as rectangular, triangular etc. has been designed on rectangular fin array. Natural convection heat transfer for fin without notch and notched fin had been

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heat transfer because of single chimney flow pattern. On the central position, the heated air rises upward and in that case already hot air is present so there is a notched portion so that fresh air can move across that. By performing the experimentation, it has been observed that average heat transfer coefficient for fin with notched portion results in high heat transfer coefficient value as compared to fin without notched portion. Also copper material results in high heat transfer as compared to aluminum. Patro. P, Patro. B and Barik. A. K [3] had performed computational investigation for the conjugate heat transfer of pin fins inside a rectangular cavity. Triangular and circular pin fins has been considered for the CFD analysis. With high air velocity at inlet, the temperature of the bulk fluid present outside the extended surface increases in case of both fin due to the fact that high air velocity tends to increase the convective heat transfer. Conjugate heat transfer means conduction, convection and radiation effect has been considered. Up to certain limit, the velocity of air can be increased. It is so because high velocity tends to increase the pressure drop which result in decreased thermal performance of the fin. The streamlines obtained by the simulation shows that at particular velocity there is an improved mixing and more recirculation of air. Circular pin fin perform far better than triangular pin fin in terms of thermal performance such as heat transfer etc. and pressure drop across the pin fins. DhanawadeHanamant,K.N.Vijaykumar&DhanawadeKavita[4] had investigated the performance of heat transfer across the fin arrays by the use of circular perforation on the extended surface. Circular holes have been designed through fin surface. Model without perforation and model with circular perforation has been compared. The simulation is performed with the help of ANSYS Fluent. Extended surface with circular perforation results in heat transfer enhancement as compare to solid fin arrays without perforation. CFX is used to set the boundary condition for the natural convection phenomena around the fin surface. The simulation result obtained is validated experimentally. Also fin with circular perforation results in improvement in average Nusselt number.

• As fins are introduced to enhance heat transfer from a base which is at high temperature, rectangular fins are considered for analysis. Life and effectiveness can be improved with effective cooling. The air cooling mechanism is mostly dependent on the fin size. The heat is conducted through the fin and converted to air through the surfaces of the fins. Insufficient removal of heat from base

• The rectangular fin as shown in Fig. with ‗L‘ as the length of the fin, ‗t‘ as thickness of the fin and ‗W‘ width of fin and assuming the heat flow is unidirectional and it is along length and the heat transfer coefficient ‗h‘ on the surface of the fin is constant.

• Fig.1 Rectangular fin Specification

• Where,

• k = Thermal Conductivity,

• Ac= Cross Section Area of fin,

• m= Fin Parameter

• P= perimeter of fin, (2W+2t)

• 0= temperature difference, K

h= heat transfer coefficient, W/m2K

The fins with various cavities are design with the help of 3D modeling software Solid Edge ST5 with following fin dimensions. Base Plate Dimension

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Width = 55mm Height = 3mm Fin Dimension Length = 240mm, Width = 15mm, Height = 40mm

After the creation of 3D model in solid edge ST5 the next process is to go for steady state thermal analysis using Ansys workbench 14. Import the 3D model file in IGS format so that meshing can be performed. In the present case Hex dominant solid185 type of element has been used and detail information on meshed assembly as shown in Table 4.1.Steady state thermal analysis is performed using ansys workbench 14.

Length Unit Millimeters Bodies 1 Nodes 6310 Elements 3262

A. Temperature & Convection Boundary Condition Assigning boundary conditions to the meshed model Materials for the model are selected as Copper, Aluminum and Brass. Thermal conductivities of materials are 400 W/m0C, 237W/m0Cand 111 W/m0C. Ambient temperature – 3000K Base plate temperature – 500 0K Heat transfer coefficient – 12 W/m2 0C

Temperature and Heat Flux Distribution along the Fin A. Length of fin 50mm without Cavity

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Graph 1 shows the variation of fin temperature with different cavities on fin surface for various fin materials. However it is concluded that rectangular fins with semicircular cavity having Brass fin material shows more heat transfer rate on 50mm fin length.

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Graph 2 shows the variation of fin temperature with different cavities on fin surface for various fin materials. However it is concluded that rectangular fins with semicircular cavity having Brass fin material shows more heat transfer rate on 60mm fin length.

In this project an attempt is made to compare the fin tip temperatures obtained by theoretical calculations made from the basics of Heat transfer to the values obtained from simulation software ANSYS Workbench -14. A constant cross section is considered for all materials. In simulation analysis a solid Brass Rectangular fin shows much heat transfer at the end (tip) of the fin than result obtained from experimental values.

In the present work an attempt is made to find the heat transfer rate, temperature, distribution and fin efficiency, heat flux for a solid rectangular fin with different materials and fin length and following conclusions made.  The use of fin with cavity provides efficient heat transfer  Fin with cavity provide almost 2% to 21% of heat transfer enhancement as compared to fin without cavity.  Fin with brass semicircular cavity results in highest heat transfer enhancement up to 21% as compared to other fin configuration.  Effectiveness of rectangular fin with rectangular cavity is more as compared with fin without cavity.  Use of cavity on extended surface reduces the weight of material thus there will be decrement in cost of manufacturing of fin.  Temperature at the end of fin with semicircular cavity is minimum as compared to other design specification hence heat transfer is maximum.

Pardeep Sing, Harvinder lal,Baljit Singh Ubhi., ―Design and Analysis for Heat Transfer through Fin with Extensions‖ IJIRSET (An ISO 3297: 2007 Certified Organization) Vol. 3, Issue 5, May 2014. Shivdas S. Kharche & Hemant S. Farkade, ―Heat transfer analysis through fin array by using natural convection‖, IJETAE – ISSN 2250-2459, Volume 2, Issue 4, April 2012 Patro. P, Patro. B and Barik. A. K, ―CFD simulation of a conjugate heat transfer problem in a rectangular cavity”, International journal of thermal technologies, Vol. 2, No. 2(June 2012), ISSN 2277 – 4114 Dhanawade Hanamant, K.N. Vijaykumar &Dhanawade Kavita, ―Natural convection heat transfer flow visualization of perforated fin arrays by CFD simulation‖, IJRET eISSN: 2319-1163 Heat Transfer-A Basic Approach by M. Necati Ozisik - Professor, Mechanical and aerospace engineering, North Carolina State University

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Mechanical Engineering Department, Angadi Institute of Technology & Management, Belagavi, India